Recent years have seen improved control of some plant virus diseases but increased prevalence of others, fuelled in part by international movement of plant material carrying non-indigenous vectors, and increased resistance of vectors to pesticides. In contrast, the science of plant virology has advanced rapidly with the aid of user-friendly molecular biological procedures, reverse genetics and modern approaches to cell biology.
Conventionally, serological methods especially enzyme-linked immunosorbent assay (ELISA) have been used widely and successfully for detection of plant viruses and diagnosis of plant viral diseases. The nucleic acid-based methods such as reverse transcription (RT) and the polymerase chain reaction (PCR) have recently been used in tool such as microarray to detect plant virus (Bodrossy and Sessitsch, 2004, Current Opinion in Microbiology 7: 245-254; Bryant et al., 2004, The Lancet Infectious Diseases 4: 100-111). Accordingly, several degenerate primers have been designed to recognize the conserved regions of viral genomes of many virus species or the whole virus genus or family (Rose et al., 1998, Nucleic Acid Research 26: 1628-1635).
While it is possible to detect many viruses of the same genus or family by performing RT-PCR given that the genetic sequence of the virus is known, a specific unknown virus species is not effectively distinguished with the currently available technique.